/*
 * Copyright 2005-2006 The Apache Software Foundation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.nanhill.commons.id.serial;

/**
 * <code>PrefixedNumericGenerator</code> is an Identifier Generator that
 * generates an incrementing number with a prefix as a String object.
 * 
 * <p>
 * If the <code>wrap</code> argument passed to the constructor is set to
 * <code>true</code>, the sequence will wrap, returning negative values when
 * {@link Long#MAX_VALUE} reached; otherwise an {@link IllegalStateException}
 * will be thrown.
 * </p>
 * 
 * @author Commons-Id team
 * @version $Id: PrefixedNumericGenerator.java,v 1.1 2006/09/20 06:56:00 alin Exp $
 */
public class PrefixedNumericGenerator extends NumericGenerator {

	/** Prefix. */
	private final String prefix;

	/**
	 * Create a new prefixed numeric generator with the specified prefix.
	 * 
	 * @param prefix
	 *            prefix, must not be null
	 * @param wrap
	 *            should the factory wrap when it reaches the maximum long value
	 *            (or throw an exception)
	 * @param initialValue
	 *            the initial long value to start at
	 * @throws NullPointerException
	 *             if prefix is <code>null</code>
	 */
	public PrefixedNumericGenerator(String prefix, boolean wrap,
			long initialValue) {
		super(wrap, initialValue);

		if (prefix == null) {
			throw new NullPointerException("prefix must not be null");
		}
		this.prefix = prefix;
	}

	/**
	 * Return the prefix for this prefixed numeric generator.
	 * 
	 * @return the prefix for this prefixed numeric generator
	 */
	public String getPrefix() {
		return prefix;
	}

	public long maxLength() {
		return super.maxLength() + prefix.length();
	}

	public long minLength() {
		return super.minLength() + prefix.length();
	}

	public String nextStringIdentifier() {
		StringBuffer sb = new StringBuffer(prefix);
		sb.append(super.nextStringIdentifier());
		return sb.toString();
	}
}
